This invention relates to doctoring apparatus, including those of the so-called "pull through" type where flexible elongated doctor blades are advanced longitudinally across the surfaces being doctored.
U.S. Pat. No. 4,691,406, the disclosure of which is herein incorporated by reference in its entirety, discloses a pull through doctoring apparatus. The doctor blade has a length greater than the width of the surface being doctored. A blade holder applies an intermediate portion of the blade to the surface being doctored. The blade is movable longitudinally through the blade holder, and has continuing portions which extend in opposite directions beyond the ends of the holder to pay off and take up reels. Clamps act on the continuing blade portions and are adjustable between closed settings preventing relative movement between them and the blade, and open settings permitting such relative movement. A drive reciprocates the blade holder. The clamps are opened and closed in timed sequence with reciprocation of the blade holder to achieve longitudinal shifting of the blade in a selected direction across the doctored surface, from one to the other of the reels. This type of blade transfer system maximizes efficiency by eliminating lost production time normally associated with the changing of conventional "cut to length" blades.